Toán Lớp 8: Bài 1: Tính a) x^2(x^2-y^2)+ y^2(x^2+y^2) b) (a^2-ab+b^2)(a-b) làm nhanh ạ

Question

Toán Lớp 8:  Bài 1: Tính  a) x^2(x^2-y^2)+ y^2(x^2+y^2) b) (a^2-ab+b^2)(a-b) làm nhanh ạ

truonganhthi · Answer

Giải đáp:    a)=x^4 +y^4   b) =a^3 +2ab^2 -b^3   Lời giải và giải thích chi tiết:    a) x^2 (x^2 -y^2)+y^2(x^2 +y^2)   =x^4 -(xy)^2 +(xy)^2 +y^4   =x^4 +y^4   b) (a^2 -ab+b^2)(a-b)   =(a-b)(a^2 -ab+b^2)   =a^3 -a^2 b+ab^2 -a^2 b+ab^2 -b^3   =a^3 +2ab^2 -b^3

aivilanlan · Answer

Giải đáp:    $1):$   $a) x&sup2;.(x&sup2;-y&sup2;)+y&sup2;.(x&sup2;+y&sup2;)$   $= x^4-x&sup2;y&sup2;+x&sup2;y&sup2;+y^4$   $= x^4+(x&sup2;y&sup2;-x&sup2;y&sup2;)+y^4$   $= x^4+y^4$   $b) (a&sup2;-ab+b&sup2;).(a-b)$   $= a.(a&sup2;-ab+b&sup2;)-b.(a&sup2;-ab+b&sup2;)$   $= a&sup3;-a&sup2;b+ab&sup2;-a&sup2;b+ab&sup2;-b&sup3;$   $=a&sup3;-(a&sup2;b+a&sup2;b)+(ab&sup2;+ab&sup2;)-b&sup3;$   $=a&sup3;-2a&sup2;b+2ab&sup2;-b&sup3;$